Which expression is equivalent to is Measure of angle 4?

A triangle has angles 1, 2, 3. The exterior angle to angle 1 is 4, to angle 2 is 5, to angle 3 is 6.
Measure of angle 2 + measure of angle 3
Measure of angle 1 + measure of angle 2
Measure of angle 1 + measure of angle 3
Measure of angle 5 + measure of angle 6